Covers are applied to surfaces for reasons that depend on the nature of these surfaces.
Therefore, in the case of a pool such as a swimming pool, the cover can prevent pollution by leaves or animals, can save energy, water and reagents and can or should ensure the security of persons, in particular of children. In a basin for the desalination or other treatments of a fluid, a cover makes it possible to prevent dilution of liquid due to rain or excessive evaporation due to heat.
When it involves a sports field such as an outdoor clay or grass tennis court, a cover makes it possible to protect it against adverse weather conditions and in particular intermittent rain.
Moreover, a vehicle body is covered notably to ensure its stability in a suction loading caused by the movement of the vehicle and to protect it against adverse weather conditions.
Covers are also used as blinds for greenhouses, winter gardens or vehicle windows in order to prevent any overheating on the inside, and as sun protection for patio awnings.
In all situations, users usually search for an economical covering device allowing covering and uncovering that is easy, secure, reproducible and rapid and requiring a minimum of human intervention.
A first totally basic device used in the case of a swimming pool comprises an inflatable or uninflatable cover that is unwound, extended and attached manually to the edges of the swimming pool. This type of device is illustrated for example in documents U.S. Pat. No. 6,691,334, GB 2 379 163 and FR 2 652 373. It is clear that here, because of the handling and storage, only fairly small-sized swimming pools are involved.
For surfaces with larger dimensions it is possible to make use of covering devices also having a drum attached to one of the transverse ends of the surface to be protected. The cover is deployed manually by pulling, by unwinding from the drum, in order to cover the surface. The weight and the dimensions of the cover require the intervention of several people so that it is properly installed. The cover is removed by winding it up around the drum by rotation: the cover is then removed from the surface by sliding over the latter. The rotation of the drum to remove the cover is carried out manually or by means of an electric motor having sufficient power to pull the completely-deployed cover. It should be emphasized that an easy deployment of the cover, in particular in the case of a swimming pool, contributes to its safety because a laborious manipulation would hamper its use.
In the present application, “longitudinal”, “transverse” and their derivatives refer respectively to the direction of movement of the drum and to the direction of the axis of revolution of the latter.
In order to remove human intervention, (completely) automatic devices have been proposed; the cover is wound up around a motorized drum allowing its retraction, the drum being attached to one of the transverse ends of the surface to be protected. The cover is deployed by pulling it via its visible end with automatic pulling means of the rack or chain type or pulling cable with or without idler pulley, the cover if necessary being able to be guided by runners placed on the longitudinal ends of the surface to be covered; the cover then slides over the surface while covering it. Similarly, when the cover is retracted, the latter slides over the surface to be covered while being wound up round the drum. This automatic covering device is illustrated notably in the following documents: U.S. Pat. No. 3,574,979, GB 2 199 741, US 2005/0097834, CA 2,115,113, US 2001/0023506, U.S. Pat. No. 5,930,848, U.S. Pat. No. 4,001,900 and on site www.aquatop.be.
The two types of covering devices with drum mentioned above have the major drawback of sliding the cover which is dragged over the surface to be protected during its deployment and its retraction which causes premature wear and extra work due to the friction thus generated.
In order to alleviate this drawback, a new type of covering device with drum has been developed, the motorized drum now being mounted on a longitudinal translation mechanism. The latter moves the drum above the surface to be covered which makes it possible literally to “place” the cover on the surface during its deployment by unwinding it simultaneously from the drum during its longitudinal movement, and then raising it during its retraction, by winding it simultaneously onto the drum. The cover does not therefore slide over the surface during its deployment or during its retraction. The covering device also comprises a system for attaching the cover at one transverse end of the surface to be covered so that the translation and the rotation of the drum cause the cover to be unwound or wound up above the surface to be covered.
Examples of automatic devices of this type are disclosed for example in the following documents: WO 2005/026473, FR 2 900 951, DE 2 257 231, FR 2 893 651, FR 2 789 425, FR 2 743 502, EP 1 719 858, and on the site www.kimbay.fr. Moreover, a completely manual variant of the drum mounted in longitudinal translation is illustrated in documents WO 2007/036625 and U.S. Pat. No. 4,195,370.
The covering devices with movable drum illustrated above provide only one attachment of a transverse edge of the cover at a transverse end of the surface to be covered, the opposite edge remaining secured to the drum. No attachment system for the longitudinal edges of the cover is provided. In particular, in the case of a swimming pool, people being engaged on the cover would not be retained by its longitudinal edges and could therefore be thrown into the water. Moreover, the lack of seal of the cover on its longitudinal edges may promote small animals such as mice or snakes getting into the swimming pool.
Another automatic device with movable drum is disclosed in document FR 2 803 769. The latter provides, in contrast, a system for attaching the longitudinal edges of the cover consisting of sections of grilles rising and then folding over section by section on said longitudinal edges of the cover while holding these edges inside a gutter progressively as the cover is unwound. In this design, the longitudinal edges of the cover are pinched without being locked, which provides less security in particular in the case of swimming pools.
In the field of vehicle body covers, the longitudinal edges of the covering sheets must be securely attached to the perimeter of the latter so as not to open when the vehicle travels at high speed.
Similarly, an awning—notably an outdoor awning—of a greenhouse or a winter garden, or a cover for a desalination basin must withstand gusts of wind that are sometimes considerable.
The need therefore remains for an automatable surface-covering system that reduces friction and makes it possible to firmly attach the cover to the surface over a large portion of its perimeter.